Transmission control system



Jan. 6, 1953 L. a. FORMAN TRANSMISSION CONTROL SYSTEM Filed July 24, 1951 2/ INVENTOR. 10245 3 fi'ormdrz.

BY 8 w a 4 M J fifrofi/yt/a Patented 'J an. 6, 1953 UNITED. STATES PATENT OFFICE 2,624,208 TRANSMISSION CONTROL SYSTEM Louis B. Forman,

Chrysler Corporation,

Detroit, Mich., assignor to Highland Park, MiOlL, a

corporation of Delaware Application July 24,1951, Serial No. 238,301

9 Claims.

This invention relates to motor vehicles and refers more particularly to power transmissions and control systems therefor.

My invention has particular reference to transmission control systems wherein the disengage ment of positively engageable drive control ele-' ments is facilitated by relieving thetorqueload on theseelements as by momentary interruption of theengine ignition systern. Examples of transmissions of this character are described in the patents to Syrovy et 1. 2,490,604, granted December 6, 1949, It has been customary, as shown by the aforesaid patents, to provide a shiftable drive control Carl A. Neracher et al. 2,455,943, granted December 14, 1948, and Augustin J elementof toothedcharacter arranged to interengage with a secondtoothed drive control element after passing through a toothed blocker.

Engagement occurs upon synchronism obtaining between the drive control elements subsequent to engine deceleration by accelerator releasing,

movement, and the shiftable element is adapted to be unloaded, as described above, to facilitate its disengagement from its companion drive control element.

The drive control elements are generally so 7 arranged in the transmission that upon relative engagement under governor control at or above a predetermined vehicle speed, there is provided a fast speed ratio drive through the transmission, usually a direct drive, and when relatively disengaged under governor control below a predetermined speed, or by kickdown means such as accelerator actuated switch means overruling the governor,- there is provided another speed ratio drive which is usually a slower speed ratio drive than the first mentioned one.

Also customarily provided are prime mover or differential. pressure .servomotor means which may comprise a spring and a hydraulic or vacuum operated motor having a movable piston, for controlling shift of the shiftable drive control" element through an associated shift rail or lever system. In the case of the hydraulic system, as typified by the Syrovy et al. patent aforesaid, pressure fluid acting upon'the piston will cause it to compress a disengaging spring and an engaging spring, and build up sufficient available force in the latter to move the shift rail and by it the shiftable drive control element against its blocker and then into engagement with its com panion drive control element when synchronization of the drive control elements subsequently occurs. 1

In the case of the vacuum power system, as typified by the Neracher et al. patent, vacuum is utilized to cause the piston to compress a disengaging spring and through a rod extension of the piston, unload an engaging spring previously tensioned by operation of the rod, the latter spring in turn acting upon a lever to effect movementofthe .shiftable element against its blocker and "intosubsequent' engagement with its companion drive control element when the drive control elements obtain synchronism.

Transmission systems of the aforesaid typical character also usually include electromagnetically controlled valving for controlling venting (admission of atmospheric pressure) of the servomotor piston such that when the actuates the piston to effect disengaging shift of the Shift? and operation of the motor is vented, the disengaging spring able drive control element accompanied by ignition interruption, the latter occurring'as an incident to available lost motion operation of the piston relative to the shift rail in Syrovy et al., and the piston rod relative to the lever operating member in Neracher et al.

Customarily there is also provided an ignition interrupter switch operated by movement of the piston in Syrovy et al. or by the piston rod in Moreover, as in the above Neracher et. al. patents, there is provided an electrical system intended to accomodate interruption of the engine ignition only during the disengaging stroke of the piston, it being so arranged that even though the ignition interruption switch closes on the return (engaging) stroke, the ignition is not ordinarily grounded out because at such time neither of the parallel arranged kickdown and governor switches which are arranged in series with the ignition interrupter switch and in series with the valve solenoid in a parallel circuiting is closed. Hence firing of the engine is not usually; interrupted during acceleration from vehicle standstill in the slower speed ratio drive.

Although the foregoing described arrangements have in general been satisfactory, they have been open to one or more unforeseen conditions of operation which it is desirable to avoid,

In use, in the arrangement disclosed by Neracher et al. and Syrovy et al., especially where a higher resistor type of ignition harness has been employed, some lurching of the vehicle has been noticeable in vehicle operation during upshifts; It is believed that in a circuiting wherein actuav tion of the interrupter switch places the ignition primary coil and the solenoid of the control valve in parallel circuits, the solenoid coil acts as a parallel impedance of low value to the primary coil of the ignition and causes the spark delivered by the secondary at the plugs at the time of current fiow thereto to be weakened. In this connection, it may be observed that under, normal engine operation the higher the engine R. P. M.," j the lower is the secondary voltage, and since the upshift takes place at a substantial R. P. M. the

effect of thelow impedance is to weaken the spark suffi-ciently so that it may be unable to keep the 1 engine running momentarily, as by causing'the engine to misfire. This condition can occur, for

example, in the Neracher et al. arrangement and in the Syrovy et al. system when the relay coil of the latter has a low impedance effect on the ignition primary.

An object of my invention is to provide an im- 3 proved ignition interruption control adapted for use, for example, with a transmission control system of the types disclosed in the aforesaid patents and which is capable of operation without weakening the ignition during the return, i. e., upshift stroke of the piston.

transmission shift control system having means for interrupting the engine ignition when eifect-,

ing a downshift, but which system inhibits weakening of the ignition spark intensity during the upshif ting operations.

Still another object is to provide a transmission control system including ignition interrupting, means and speed responsive and accelerator controlled differential pressure fluid means for effecting shifts in the transmission, wherein the control circuiting is arranged to make the control circuiting for the shift effecting means independent of the ignition interruption control circuiting.

Other objects and features of my invention will be apparent from the following description wherein:

Figure l is a diagrammatic plan View of the driving power plant for the vehicle;

Figure 2 is an elevational view partly in section of my invention as applied to a semi-automatic four speed forward and reverse transmission, a part of the control system being substantially illustrated, the manually operable clutch sleeve being shown in its forward or high range position for starting the vehicle from rest, and the power shiftable mechanism and power operable clutch sleeve being shown in the released position of the latter; and

Figure 3 is an elevational view similar to a portion of that in Figure 2 and showing the power shiftable clutch sleeve in its direct drive or engaged position and the power shifting mechanism in the corresponding position.

In the drawings in which similar numerals indicate similar parts of the structure, Figure 1 illustrates a typical motor vehicle power plant having a conventional engine A for transmitting power through a propeller shaft It to drive the rear ground wheels II. In the housing B there may be provided a fluid power transmitting device, such as a fluid coupling arranged in tandem with a master friction clutch of known type, the latter being releasable to uncouple the engine from the transmission by operation of a conventional clutch pedal I2. Rearwardly of the housing 13 is a transmission C which may be of-any type incorporating positively engageable drive control elements of a character usually subject to substantial thrust or torque load in operation, the latter conditions makin the use of some form of unloading means desirable to insure release of the drive control element when a speed change requiring disengagement of these elements is necessary.

The transmission C may be'of Various known types. For purposes of illustration I have shown in Figure 2, a commerical form of four-speed and reverse countershaft underdrive transmission. This transmission comprises an input or driving shaft it which receives drive from the engine A by way of the clutch assembly B, and an output or driven shaft [4 which is adapted to transmit drive to the propeller shaft It. The driving shaft [3 carries the main driving gear or pinion I5 and a set of positive jaw clutch teeth is which are adapted to be engaged by the teeth of a jaw 4 clutch sleeve D; As will behereinafter seen, the sleeve D together with the clutch teeth l6 comp-rise relatively movable drive control elements for effecting stepup and stepdown manipulation of the transmission.

The clutch sleeve D is slidably splined on teeth, not shown, of a forward hub portion of the high or third speed gear 22 which i rotatably journalled on the driven shaft It and adapted to be clutched thereto through a jaw clutch sleeve F slidably splined on a hub, not shown, drivingly carried by the shaft M and interengageable with jaw clutch teeth 25 carried by the gear 22. The

forward shift of sleeve D for clutching with teeth- It is normally controlled or impeded by a'toothed blocker E whereby clutching is limited to synchronous relationship in the speeds of rotation 01'- gears i5 and 22 and, in the particular construction illustrated, limited to engine coast conditions obtainable by accelerator releasing movement to secure deceleration of the engine. The blocker E is journalled on a conical surface, not shown, carried by the shaft [3 against which it is frictionally urged by a spring, also not shown,

and has a limited lost motion connection with the sleeve D or gear 22 whereby it may rotate to place its teeth in blocking relation to the teeth of sleeve D whenever the gear l5 rotatably leads or lags the sleeve D. When sleeve D moves-past the blocker E into engagement with the clutch teeth I6, the ears l5 and 22 are placed in a twoway direct drive relationship.

Gear 22, as stated above, is loosely journalled on the driven shaft M whereas the pinion I5 is part of the input shaft I 3. Also loosely journalled on the output shaft I4 is a low or first speed gear 21 having jaw clutch teeth 28 engageable by the sleeve F. Associated with thesleeve F on each side thereof is any commercial type of blocker synchronizers 29 such that clutch F may be shifted from a neutral positiondisengaged from teeth 26 and 28 forwardly to a high range position to synchronously clutch shaft M with the high speed gear 22 through the teeth 26 or rearwardly to a low range position to syn-.

chronously clutch shaft l4 with the low speed gear 21 at its teeth 28. Manual shifts of the sleeve F are facilitated by release of the main clutch at B by means of the clutch pedal I2.

Gear 22 is also adapted to be driven from gear l5 at a speed different from 1:1 and to this end I have shown a countershaft type one-way reduction driving means between these gears. This drive comprises the coaxially rotatable countershaft gear 30 and cluster gear 3 l, wheels 32; 33' respectively, in constant mesh with gears I5; 22, and 21 and an overrunning roller clutch G 0perably interposed therein between the gear 30 and cluster 3|. A stationarily mounted countershaft 34 provides a journal support for the countershaft gears. Assuming the usual clockwise rotation of shaft 13' as viewed when looking from front to rear of Figure 2, then overrunning clutch G will automatically clutchgear 30 and 1 together when gear 30 is driven coun- As thus far described, it will be apparent that with the parts arranged as in Figure 2, sleeve F being then in high range position engaged with teeth 26, drive of shaft l3 will cause the output shaft M to be driven at a reduction drive (third speed) through the gears I5, 30 overrunning clutch G, gears 32, 22 and sleeve F. Should the sleeve D be biased forwardly during this reduction drive, blocker E will obstruct sleeve D in an intermediate position of its shift preventing ratcheting of its teeth with the teeth l6. However, if the driver releases the engine throttle control in the form of the usual accelerator pedal then, as will be apparent, overrunning clutch G will allow gear l5 and teeth IE to slow down relative to the sustained speed of gear 22 and when the speed of gear |5 reaches synchronism with that of gear 22, blocker E will move to an unblocking position and allow sleeve D to move further forwardly to clutch its teeth with teeth I6 to the position shown in Figure 3, to provide the direct drive (fourth speed), clutch G continuing its overrunning operation. Upon return of sleeve D to disengaged position shown in Figure 2, followed by speeding up the engine, overrunning clutch G will automatically engage to restore the reduction drive.

When clutch sleeve F is shifted rearwardly to low range position to clutch gear 21 to shaft I4 an overrunning slow speed drive (first speed) is transmitted from the shaft |3 to the shaft I4 by way of the gears I5, 30, overrunning clutch G, gears 33 and 21 and sleeve F. At such time as the sleeve D is biased forwardly and the shaft I3 is allowed to slow down to permit the teeth Hi to become synchronized with the sleeve D, the sleeve will move past the blocker E and clutch with the teeth Hi to establish a two-way relatively fast speed drive (second speed) in the low range, which drive will be from the shaft l3 through the sleeve D, gears 22 and 32, gears 33 and 21, and clutch F to the shaft M, the clutch G overrunning by reason of the cluster 3| rotating at a higher speed forwardly than the gear 30.

It will be understood the driver may start the vehicle from rest in the low range drive and subsequently shift to the high range incident to momentary release of the master clutch and this either prior to or subsequent to engagement of the clutch D. Most drivers, however, usually start the vehicle from rest in the slow speed ratio of the high range and at a subsequent higher speedobtain the automatic upshift to direct drive by momentary release of the accelerator pedal described above.

A more complete description of the transmission specifically illustrated in this application and its method of operation is set forth in the patent to A. J. Syrovy et al. 2,490,604 aforesaid.

A speed responsive governor means 0 is pro-- vided to control forward bias of the sleeve D as well as rearward bias thereof as will be presently more apparent. Moreover, during drive in either second or fourth speeds referred to above, a downshift to first or third speeds respectively may be effected by way of overruling the governor 0 through driver depression of the acclerator pedal M to substantially wide open throttle position, which operation is referred to in greater detail below.

As seen in Figure 2, I have illustrated a servomotor H by which to obtain power actuation of the clutch sleeve D, the motor here illustrated being of the pressure differential and spring operated type and in the disclosed embodiment functioning by means of fluid. pressure. This motor preferably comprises a cylinder 36 slidably receiving a piston 31. The piston slidably receives a shift rail or rod 38 mounted to operate in the guideways 39 and 40. Fixed to rod 38 is a yoke 4|, a hub portion 42 of which is secured to the rod 38 by means of a dowel screw 43. The rod 38 and yoke 4| constitute motion transmitting means S for the sleeve D, thev yoke 4| as seen in Figure 2, having fingers 44 engaging in a groove 45 of the sleeve D to effect shift thereof.

A relatively small preloaded engaging spring 46 surrounds the rod 38 and is disposed between the hub of piston 31 and the hub 42 of the yoke 4|. This spring 46 provides a lost motion thrust transmitting connection between the piston 31 and the hub d2 of the motion transmitting means S such that the piston 31 may be moved forwardly (to the left in Figure 2) for its power stroke, the piston 31 continuing its forward motion by fluid pressure even after the clutch D has been moved against the blocker E until the lip 41 of the piston uncovers the relief portion 48 of the cylinder 36 whereupon forward movement of the piston 31 will cease, the fluid pressure being then expended through the relief port 58.

During the said forward movement of the piston 31 the engaging spring 46 is compressed and urges the rail 38 through the hub 62 of the yoke ll forwardly thus in turn shifting the clutch sleeve D to its intermediate position blocked by the blocker E. Subsequently upon synchronous rotation of the teeth I6 and sleeve D being obtained in response to accelerator releasing movement, the sleeve D is moved through the blocker E into engagement with the teeth lb of the drive pinion l5, which is its fully engaged upshifted position shown in Figure 3, establishing the previously described direct drive between the shaft i3 and gear 22.

A relatively large preloaded downshift or kickdown spring 59 is disposed between an abutment ring 50, located at the forward end of the cylinder 36, and the piston 31. This spring serves to return the piston 31 and sleeve D from their Figure 3 positions to their downshifted or disengaged position shown in Figure 2. It will be observed from Figure 3 that the piston 31 when in its furthest forward position shown in this figure uncovering the port 48 has moved further than the shift rail 38 such that a gap 5| is created between the piston 3i and a shoulder 52 of the portion 53 of the shift rail. This gap 5| facilitates a lost motion movement of the piston 3'! relative to the shift rail 38 prior to disengaging move ment of the sleeve D which can only commence following abutment of the piston 37 with the shoulder 52. As previously noted, forward movement of the piston 31 is stopped upon uncoveringthe port 48, the latter permitting any excess pressure required to hold the piston 31 in its furthest position to be relieved and preventing the building up of such excess pressure in the cylinder.

The pressure fluid supply system is shown in Figure 2 and comprises a suitable supply source 6|), which is usually the transmission sump. A pump Q of the rotary gear type is mounted on the shaft H3 and has its rotor 6| driven by that shaft, oil being drawn from the supply source 69 through the conduit 62 to the pump inlet 63 and is delivered under pressure at the pump outlet 64 to the .conduit 65 and then to the passage 66 under control of a ball valve K. A relief valve, generally designated by the numeral 61 and provided at the pressure side of the pump between the outlet 64 and the ball valve K, serves as a.

relief valve in the event the valve K is not open in normal operation of the transmission to thereby permit pressure fluid trapped behind the piston 3? to be dumped back into the transmission sump at through the conduit Sic.

When the valve K is closed, oil under pressure is forced directly from the pump through the passage 56 to the cylinder 35 where it moves the piston 37 forwardly to effect forward movement of the shift rail 38 in the manner described above whereby the shift sleeve D is operated from its disengaged position in Figure 2 to its engaged position of Figure 3 to establish second or fourth speed ratio drive depending upon whether the clutch F is engaged with the first speed gear 2? or with the third speed gear 22.

Valve K is closed by bias of a valve spring 511 acting against a ball to close a discharge port 'Hl opening into a passage ii draining to the sump or supply source as. The valve K is actuated to its open position under control of an electromagnetic device comprising a solenoid L having a plunger 62 connected with the movable core of the solenoid. The valve K is closed when the solenoid L is deenergized. The spring 82 then actuates the ball $9 against a seat id to close the port 16 and effects movement of the solenoid plunger 12 to its retracted position. The valve K is open when the solenoid L is energized, the solenoid core then moving the plunger ?2 downwardly to push the ball 59 off the seat is of port :8. The oil may now flow from the pump Q through the conduit es; port is, passage 7 9, back to the sump 69.

When the valve K is open, it is impossible for sufficient fluid pressure to develop in the passage 56 to move the piston 37 against the force exerted by the piston return spring which then maintains the piston at the extreme rearward position of its capable movement. Hence the piston 33 is actuated by fluid pressure only to establish second and fourth speeds respectively at which time the valve K is closed and the solenoid L deenergized. Figure 2 shows the valve K in its open position and the piston 3? in its position retracted by spring 49, and Figure 3 shows the valve K in its closed position and the piston 3? in its furthest forward position under control of the pressure fluid.

-Energization and deenergization of the solenoid L is brought about by operation from one position to another of either or two control members, one actuated in response to vehicle speed, and the other in response to manipulation by a driver control member. One of these control members is a switch N operated by the governor O, and the other is a kickdown switch generally designated by the letter P.

As noted above, prior control circuits and structures providing the ignition primary coil and the solenoid L in parallel arranged circuits made it possible for the solenoid L to act as a parallel impedance of low value to the primary coil and weaken the spark delivered by the secondary at the plugs 74 when current flow thereto took place. A feature of the present invention is to overcome this diinculty and in order to accomplish this I preferably employ what are in effect double pole single throw switches in the governor and kickdown mechanisms and provide suitable electrical circuit means for efiectuating the control operation of the governor and kickdown switches over the-solenoid L.

As seen in Figure 2, a suitable source of electrical 'energy,-for example; a'storage battery 15 has one side'grounded as at 1'6 by-a conductor' l'l and its other side connected by a conductor 18 through an ammeter' F9 to the ignition switch- 80. A conductor 8! connects the ignition switch with one terminal 82 of the solenoid L, the other terminal 83 of the solenoid L being connected-by a conductor 84 with a terminal 85 of one pole of the double pole single throw governor switch'N, the other terminal 8'? of this pole being connected to a ground 88 by a conductor 89. From the governor switch terminal85 a conductor *9il'extends to a terminal SI of one pole of thedou'ble pole single throw kickdown snap switch'P; the other terminal 92 of this pole being connected to a ground 93 by a conductor 94.

The ignition mechanism generally designated by the letter J is of conventional type and includes an ignition coil 95, a distributor 98, and a breaker Hid. From thepriinarycoil l02-an ignition grounding circuit is provided'thatextends through the conductors 104, I96 to a terminal I88 of a normally open interrupter switch T and then from a terminal I'IB thereof to enterminal H2 of the otheror second pole of the governor switch N by-means of a conductor H4. The second terminal H6 of this second pole-is connected to ground 88 provided by the governor 0 through conductors I i8, 89, it being noted that the terminal H6 is in effect common with the terminal 37. The switch T may also be connected with ground 93 of the kickdown switch. Thusa conductor I29 connects theconductor H4 anda terminal 922 of the other or second pole of the kickdown switch P, the second terminal I24 of'the pole connecting with ground 93 through conductor 9 3. It will be noted that the terminals 92 and E24 are in eiTect common terminals.

The governor switch N is closed by: a movable switch bar comprising-conductor sections I26 and I28 insulated from each other. The bar-is operated by an insulated sliding sleeve I30 of the governor O. The switch N is closed when the'section i26 bridges the terminals H2, H6 and'the section 52B bridges the terminals 85, 81.

The kickdown switch P is of the snap type and has a pivotal switch bar comprising insulated conductor sections I32, I34 which close the switch when the section I32 bridges the terminals I22, I25 and the section I34 bridges the terminals SI. 92. The switch bar, as shown in Figure 2, is held in open position under control of acoil spring I40 which also biases the accelerator-M to its released position.

The accelerator M is suitably connected with the usual engine carburetor throttle valve by means including linkage I42, 144 whichserves to open and close the throttle valve. Interposed'in the throttle valve operating linkage is a lever I50 pivotally supported at I 5| and having spaced fingers or projections I52, I53 for operating the actuating finger I54 of the snap switch P. The mechanism is preferably arranged such that in operation, the switch finger 154 is engagedby the lever projection I52 as the throttle valve in response to depression of the accelerator M approaches its full open throttle position, so that the switch P is closed with snap action during approximately the last 5 or so of the throttle opening movement. It will be understood that the operation of this switch maybe adjusted to occur subsequent to full open throttle position by the provision of suitable lost motion mechanism such as disclosed in the patent to Neracher-et a1.

2,455,943. When the-accelerator M is released; the finger I 53-comes into contact Withlthe acturating. finger I54 of the switch near the fully released position of the accelerator to actuate the switch P to its open position, again by snap action, the parts being so arranged that the switch P will be opened by finger I53 whenever the accelerator pedal is fully released.

' It will be observed that in the described circuiting, the ignition interruption circuit is by means of the double pole switches made independent of the solenoid L circuit so that when the interrupter switch T is closed during upshifting, a common ground will not be then provided for the primary ,coil I62 and the solenoid L.

It will also be noted that the piston 31 has its outer skirt I 60 reduced at I6I adjacent the cammed portions I62, I63 forcontrolling operation of the ignition interrupter switch T of known type. This switch is biased to open position by a. spring I64 and has its operating stem'engaging a ball I66 so arranged in association with the piston portion I 60 that switch T is open when the piston .is inthe Figure 2 position and in the Figure 3 position of forward movement of the piston. However, as the cammed portions I62, I63 move 1 by the ball I66 in either direction of movement of the piston, the ball I66 is actuated to close the switch. Thus in the forward movement of the piston the cammed portion I62 operates the ball and the cammed portion I63 permits the ball to return to the open position of the switch by dropping in the reduced portion I6I of the piston, the ball being shown in this position in Figure 3. On the downshifting movement of the piston the cammed portion I 63 actuates the ball I66 to close the switch T and the cammed portion I62 permits the ball to return to the open position of the swtich T.

V V The operation of the transmission and control system will now be described. Let it be assumed that the vehicle is at a standstill with the manual sleeve F shifted forwardly in engagement with the teeth 26 of the third speed gear 22, as seen in Figure 2. At this time the governor switch N will be closed and provides a circuit from the battery I to the ground 88 by way of the conductors SI and 84 and solenoid L thus energizing the latter whereby the solenoid rod I2 maintains the ball 69 of the valve K in its down position venting the motor H so that spring 49 holds the clutch sleeve D in the position shown in this figure. The interrupter switch T is open as shown, the ball operator I66 thereof being free of the skirt switch P isalso open since the accelerator pedal is released.

By depressing the accelerator pedal within its normal operating range, the vehicle is driven in third speed ratio drive. At some predetermined speed of vehicle travel, for example 12 to 14 M. P. H. (6 to '1 M. P. H. in first speed), the governor 0 actuates the switch N to open position thus breaking the circuit between the ground 68 and the conductors 64 and I I4 respectively. The solenoid L is thereupon deenergized and the valve K closed by operation of the spring 68 which moves the ball 69 to close the port 1|] at the entrance of the return passage I I, thus permitting pressure to be built up by the pump Q in the passage 66.

At the momentof operation of the solenoid L, the interrupter switch T is in open position, the .parts being in the position shown in Figure 2. When the fluid pressure builds up sufiiciently, the

' piston 31 moves forwardly for its upshift stroke andcomes to rest at the position shown in Figure s'wnere" the relief T port 48' is uncovered by the I60 of the piston 31. The kickdown' piston to relieve the fluid pressure and maintain the piston at this position. The forward movement of the piston 31 is utilized in compressing the springs 46 and 49. Initially, the spring 46 moves the motion transmitting means S and thereby the sleeve D to its blocked position against the blocker E. Then 10st motion'movement takes place between the piston 31 and the shift rail 38 during which the springs 46 and 49 continue to compress. During the lost motion movement, the skirt I66 of the piston has its cammed portion I62 move past the ball I66 of the switch T camming the ball I66 upwardly to close the switch T, the switch T remaining closed until the cammed portion I63 of the skirt I60 passes under the ball I66 at which time the ball drops i into the recess'or relief portion ISI of the piston to reestablish the switch T in open position. Thereafter upon accelerator release to synchronize the speeds of the'sleeve D and the clutch teeth I6, the sleeve D is moved by the spring 46 acting upon the yoke 4| -of the motion transmitting means S, to its engaged position shown in Figure 3. During this engaging movement, the rail moves forwardly relative to the piston 31, the latter remaining in its position shown in Figure 3, uncovering the port 48.

Although the switch T is operated during the forward movement of the piston, the spark delivered by the secondary coil of the ignition system at the plugs I4 will not be weakened for the reason that the circuiting for the solenoid L is maintained independent of the ignition circuiting by the switch mechanism N, it being impossible at this time to condition the solenoid L and the primary coil I62 in a parallel circuiting through operation of the switch T.

Once established in fourth speed, a downshift to third speed is effected either by manually closing the kickdown switch P by means of the accelerator pedal M or by the automatic closing of the governor switch N when the speed of the vehicle drops below the upshift speed set for the transmission. For example, when the driver'desires to manually effect the downshift from fourth speed to third speed, he fully depresses the accelerator M. During this operation, for example as the throttle approaches its full open position, the switch P is closed. Since the engine is then delivering its full power, it is desirable to effect torque relief at the teeth I6 to facilitate the release of sleeve D for the downshift. At this time the switch T is in itsFigure 3 open position with the ball I66 in the recess I6I of the piston which is then in'its positionadjacent the relief opening 48. Moreover, the motion transmitting means S is in the fully engaged positionof the sleeve D.

' Closing of switch P applies the ground 93 to the solenoid L circuit from the battery I5 causing energization of the solenoid L and opening of the valve K to vent the motorI-I.

As noted above, the interrupter switch T which connects by the conductors I64, I66 with the primary winding I62 of the ignition coil 96,is in series with the ground 96 established by the kickdown switch P through the conductors H4 and I20. Also when pressure is vented in the cylinder 3'6,the sleeve D usually initially remains engaged by reason of the engine torque on its teeth while the piston 3? begins its return movement under urging of the spring 49. Hence the piston will initially take up the lost motion 5| between itself and the shoulder 52 of the end portion 53 of the rail 38. During this lost motion movement the cammed portion I63 of the piston moves under :theiball L65 :ofthe switch .T urging the ball'up- "VVaIZdIY'ItO close theswitch T and, complete the circuit between-the primary winding 102 and the ground 960i the kickdown switch P, thereby :grounding the ignition system. The engine now "missing'fire, unloads the torque on the teeth of "the:clutch,member l6 and the teeth of the sleeve Ill-thereby permitting the spring 49 to effect disengagement of the sleeve D by moving the piston i3;1 and1rail 38iurther rearwardly and to complete ithe. rearward or return stroke of the piston 31, rail I38 :and sleeve D back to the position illustrated :in Figure 2. During this return movement the cammed portion I62 of the piston passes under the ball lfifilof the switch T permitting the switch 'toreturn to its open position restoring the igniztion gto, normal-operation. When subsequently :the1accelerator'pedal M isreleased sufiiciently to open-the switch P, .fourth speedratio drive may .zaga-in be restored as previously described pro- ":videdthe vehicle speed is still such that the governor switchlNis open.

.For the automatic downshift from fourth speed "itoithird speed under control of the vehicle gov- :ernor 0, it is only necessary'toreduce the vehicle speed'to or below the speed at which the governor switch N normally closes. Closing of the switch 'N-energizes the solenoid L by efiecting a circuit .from the battery "55 to the ground 88, the motor H is'then vented as described above with respect to the kickdown operation of the transmission and the interrupter switch T is operated as theredescribed.

When "the sleeve F is in its rearward or low range'position, the upshift and downshiit movement of the sleeve D between first and second speed positions will be the same as that set forth for operation of this sleeve between third and fourth speedpositionswhen the sleeve F is in its {high range-setting. However, since the governor 1 -Oisdriven from the countershaft as at till, I?! in Figure 2, the governor Will function at a somewhat lower car speed depending upon the -.gearratiosfor 'first'and second speed as com- ;pared with third and fourth speed as will be readily understood. It will be understood, however, that the governor driving means we may,

if desired, be on the driven shaft M.

From the foregoing description of my invention, itwill be apparent that I have provided a novel ignition interrupter control sfystem and structure for transmissions having both govcrnorand manually controlled downshifting where ignition interruption for disengaging engaged lutch elements is obtained as required, and operationof the interrupter means during upshiitring operations will not cause any weakening .of the spark delivered by the secondary of the '1. In a power transmission for driving a vehicle having an engine provided with an ignition system: :a shiftable transmission drive control element shiftable from a first position disengaged relative to another drive control element to a second position of engagement with said other ele- "12 ment and shiftable out "of said second position when operation of said ignition systemismo- 'mentarily interrupted to relieve the thrustload at said shiftable element, motion transmitting means for shifting :said shiftabledrive control element, actuating means operable upon said motion transmitting means .for effecting shift of said shiftable drive control element between its two said-positions, :electromagnetic'means for controlling said actuating means, governor means for "controlling said electromagnetic means and ignition-interruption switchmeans operable by said actuating means, :said governor :means'ineluding a pair of normally open "switches'operable when closedlfor controlling shift of .said :shiftableelem'ent' from its said. first'positionto Lits isaid second "position, :one idfi'SEii'd'iSWitGheS :he'ing in series with said -ignition interruption means andlthe other being iii-series with said electro- "magnetic ;means.

'2. In a power transmission .fordrivin'g :a wehiclefhaving an -.engine' provided with an "ignition system; :a ishizftable transmission drive :control element shiftable'from 'afirst'position disengaged :relative to another drive control element to a means, saidgovernor means including -a pair of substantially simultaneously operative normally open switches operable when closed for controlling-shift of said shiftable element from its said first to its said second position, ignitioninterrupting switch means operable by said actuating means, circuit means including said interrupting switch and one-of said pair of switches in series, and other circuit means including said electromagnetic meansand the other of said pair of switches in series.

3. In apower transmission for driving a vehicle having an engine provided with an ignition system; a shiftable transmission drive control element shiftable from a first position disengaged relative to another drive control element to a second-position of engagement with said other element and shiftable out of said second position when operation of saidignitionsystem is momentarily interrupted to relieve the thrust load at said shiftable element, motion transmitting means for shifting said shiftable drive control element, actuating means operable upon said motion transmitting means for effecting shift of said shiftable drive control element between its two said positions, electromagnetic means ior controlling said actuating means, ignition interrupting switch means operable by said actuating means, governor means including a double pole single throw switch for controllinga pair of electrical circuits, one of said circuits including said ignition interrupting switch means and the other including said electromagnetic means.

4. In a power transmission for driving a vehicle having an engine provided with an ignition system; a shiftable transmission drive control ele- .ment shiftable from a first position disengaged relative to another drive control element to a second position of engagement with said other element and shiftable out of said second position when operation of said ignition system is momentarily interrupted to relieve the thrust load at said shiftable element, motion transmitting means for shifting said shiftable drive control element, actuating means operable upon said motion transmitting means for efiecting shift of said shiftable drive control element between its two said positions, electromagnetic means for controlling said actuating means, ignition interrupting switch means operable by said actuating means, governor means including a double pole single throw switch, each pole comprising a pair of contacts and a bridging conductor operable for electrically connecting said contacts, one contact of each pair of contacts being grounded, the other contact of one pole electrically connecting said ignition interrupting switch means and the other contact of the other pole electrically connecting said electromagnetic means.

5. In a, power transmission for driving a vehicle having an engine provided with an ignition system; a shiftable transmission drive control element shiftable from a first position disengaged relative to another drive control element to a second position of engagement with said other element and shiftable out of said second position when operation of said ignition system is momentarily interrupted to relieve the thrust load at said shiftable element, motion transmitting means for shifting said shiftable drive control element, actuating means operable upon said motion transmitting means for effecting shift of said shiftable drive control element between its two said positions, electromagnetic means for controlling said actuating means, ignition means including a primary coil and an ignition interrupting switch in series with said coil, said switch being operable by said actuating means, governor means including double pole single throw switch means, and manually operable means including double pole single throw switch means, each pole of said double pole switch means comprising a pair of contacts and a bridging conductor operable for electrically connecting said pair, one contact of each pair of contacts being grounded, the other contact of one pole of each said switch means electrically connecting said ignition interrupting switch, and the other contact of the other pole of each said switch means electrically connecting said electromagnetic means.

6. A power transmission as claimed in claim wherein the switch means of said manually operable means is operable by the accelerator pedal.

'1. In a power transmission for driving a vehicle having an engine provided with an ignition system; a shiftable transmission drive control element shiftable from a first position disengaged relative to another drive control element to a second position of engagement with said other element and shiftable out of said second position when operation of said ignition system is momentarily interrupted to relieve the thrust load at said shiftable element, motion transmitting means for shifting said shiftable drive control element, differential fluid pressure motor means including a piston, operable upon said motion transmitting means for effecting shift of said shiftable drive control element between its two said positions, a solenoid controlled valve for controlling operation of said motor means, ignition means including a primary coil and an ignition interrupting switch, and speed responsive governor means including switch means for simultaneously controlling the grounds of a pair of independent circuits, one of which includes said solenoid and the other of which includes said interrupting switch.

8. In a power transmission for driving a vehicle having an engine provided with an ignition system; a shiftable transmission drive control element shiftable from a first position disengaged relative to another drive control element to a second position of engagement with said other element and shiftable out of said second position when operation of said ignition system is momentarily interrupted to relieve the thrust load at said shiftable element, motion transmitting means for shifting said shiftable drive control element, differential fluid pressure motor means including a piston, operable upon said motion transmitting means for efiecting shift of said shiftable drive control element between its two said positions, a solenoid controlled valve for controlling operation of said motor means, ignition means including a primary coil and an ignition interrupting switch operable by said piston, speed responsive switch means operable for grounding a pair of circuits, one of which includes said solenoid and the other of which includes said interrupting switch, and driver operable switch means operable for groundin the same circuits.

9. In a power transmission for driving a vehicle having an engine provided with an ignition system; a, shiftable transmission drive control element shiftable from a first position disengaged relative to another drive control element to a second position of engagement with said other element and shiftable out of said second position when operation of said ignition system is momentarily interrupted to relieve the thrust load at said shiftable element, motion transmitting means for shifting said, shiftable drive control element, a hydraulically operable motor including a piston, operable upon said motion transmitting means for effecting shift of said shiftable drive control element between its two said positions, a valve for controlling said motor, a solenoid for controlling said valve, ignition means including a, primary coil and an ignition interrupting switch, cam means on said piston for operating said switch, speed responsive switch means operable for simultaneously grounding a pair of independent circuits one of which includes said solenoid in series with this switch means and the other of which includes said interrupting switch in series with this switch means, and accelerator operable switch means in parallel with said speed responsive switch means operable for grounding the same circuits.

LOUIS B. FORMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Gilfillan Aug. 28, 1951 

